FOMAs II and III (functional orthopedic magnetic appliances) are newly developed orthodontic appliances utilized in the correction of skeletal C1. II and C1. III jaw malrelationships during growth spurt periods. The force units in FOMA are two rare earth permanent magnets, one in each jaw, in attractive orientation. The long term objectives of this research project are: 1. To evaluate the treatment feasibility of FOMAs II and III. 2. To compare the effectiveness of FOMA II to conventional methods. 3. To seek the optimal mechanism of FOMA to achieve functional adaptation. With regard to the last objective, two sets of hypotheses will be tested: - Treatment results with FOMA improved with a gradual stepwise mandibular displacement/or with a single maximal mandibular displacement. - Functional correction grows with increasing mandibular immobilization/or mobilization. The in vivo part of the study includes 18 females Macaca fascicularis primates in an early mixed dentition age. The animals will be divided in 6 groups (A-F) of 3 animals in each: (A) FOMA II; (B) Feedback plates; (C) The combination of feedback plates and FOMA II; (D) FOMA III Lingual; (E) FOMA III Labial; (F) Sham appliance. The three animals of each group will be sacrificed after 4, 12, and 18 months with respect to treatment phases (active, "pseudo" retention, relapse). All animals will receive unilateral facial implants for the cephalometric analysis and two Procion organic bone vital dye markers given alternatively according to the treatment phases, for the histological analysis. The in vitro part of the study includes: coating procedures with stainless steel capsules; characterizing the magnetic spatial orientation and testing horseshoe shaped magnets. Objective 1-3 will be evaluated: by comparing the subgroups to the control group (A1-3, B1-3, C1-3) vs. (E1-3) and (D1-3, E1-3) vs. (F1-3), by comparing each subgroup per se (A1-3 vs. B1-3 vs. C1-3) and (D1-3 vs. E1-3) and by comparing each group per se e.g., A1 vs. A2 vs. A3.